Thermoplastic elastomer composition and process for producing the same and pneumatic tire and hose using the same

ABSTRACT

A thermoplastic elastomer composition dynamically vulcanized to a gelation rate of 50 to 95% which is superior in heat resistance and durability while maintaining flexibility and superior in air permeation preventive property which can be efficiently used as, for example, a pneumatic tire as an air permeation preventive layer. In particular, a thermoplastic elastomer composition having a reduced particle size of the domain rubber is produced by a material having a high rubber ratio by mixing a composition (C) mixed under conditions of a ratio of melt viscosities of the rubber composition (A)/resin (B) of 0.8 to 1.2 and the formula (φ A /φ B )×(η B /η A )&lt;1.0 under conditions of a ratio of melt viscosities of the rubber composition (D)/composition (C) of 0.8 to 1.2 and the formula (φ D /φ C )×(η C /η D )&lt;1.0, wherein φ A : volume fraction of rubber composition (A), φ B : volume fraction of resin (B), η A : melt viscosity of rubber composition (A), η B : melt viscosity of resin (B), φ C : volume fraction of composition (C), φ D : volume fraction of rubber composition (D), η C : melt viscosity of composition (C), η D : melt viscosity of rubber composition (D). Further, a thermoplastic elastomer composition having an elastomer composition (A) as a dispersion phase and a thermoplastic resin composition (B) as a matrix and having a thermoplastic resin composition composed of a blend of at least two thermoplastic resins.

TECHNICAL FIELD

[0001] The present invention relates to a thermoplastic elastomercomposition, more particularly relates to a thermoplastic elastomercomposition excellent in durability and excellent in resultant tireinside appearance and air permeation preventive property and to apneumatic tire and hose using the same. The present invention furtherrelates to a process for producing a thermoplastic elastomercomposition, more particularly a process for producing a thermoplasticelastomer composition capable of providing a domain rubber having areduced particle size with a material having a high rubber ratio and aprocess for producing a pneumatic tire using the same.

BACKGROUND INVENTION

[0002] Compositions having a low gas permeation performance (gas barrierperformance) composed of thermoplastic resin/thermoplastic resin-basedblends such as a high density polyethylene resin and nylon 6 or nylon 66(HDPE/PA6.66), a polyethylene terephthalate and aromatic nylon(PET/MXD6), a polyethylene terephthalate and vinyl alcohol-ethylenecopolymer (PET/EVOH), where one thermoplastic resin is layered over theother layer to form plural layers by molding, and processes forproducing the same, are already known from Isao Hata: Kobunshi(Polymers), 40 (4), p. 244 (1991) etc. Further, an application regardingthe use of such a composition as the inner layer of a tire has beenalready filed by the present assignee (Japanese Patent Application No.7-55929). However, since these materials are thermoplasticresin/thermoplastic resin blends, while they are superior in gas barrierproperty, they lack flexibility, and therefore, such films are liable tobreak when the tire is in running.

[0003] Further, there are also examples of use of a thermoplasticelastomer composed of a rubber and a thermoplastic resin for the innerliner or a tire (Japanese Patent Application No. 8-183683), but ingeneral a flexible material superior in durability has a low heatresistance. With a thermoplastic elastomer using a thermoplastic resinhaving a melting point less than the tire vulcanization temperature as amatrix, when the vulcanization bladder is released at the end of thevulcanization of the tire, the tire inside surface is liable to becomepoor in appearance due to the thermoplastic resin sticking to thebladder, rubbing with the bladder, etc.

[0004] Research directed to the difference in viscosities at the time ofprocessing in mixing of rubbers and resins has been known in the past.Among these, the capability of reducing the domain dispersion particlesize the most in the state where the ratio of melt viscosities of therubber/resin is brought close to 1 (that is, no difference inviscosities) has been reported in S. Wu, Polym. Eng. Sci., 27(5), 1987.If using these technologies to fabricate a thermoplastic elastomerhaving more flexibility, larger strength and elongation, and superiordurability by raising the rubber ratio, while keeping the ratio of meltviscosities of the rubber/resin at 1, the rubber becomes the matrix andthermoplasticity is no longer exhibited.

[0005] In a laminate in which dynamic fatigue resistance is requiredsuch as tire, hose, when using a gas permeation preventive thermoplasticelastomer composition composed of rubber/resin dispersed therein, it isknown to obtain a balance between the flexibility and gas permeationpreventive property by making joint use of a flexible N11- or N12- nylonand superior gas permeation preventive property N6- or N66- nylon.Further, the present inventors have proposed to define the volumefraction and melt viscosity using the equation of α:

(φ_(d)/φ_(m))×(η_(m)/η_(d))<1.0

[0006] wherein the volume fractions of the continuous phase componentand dispersion phase component in the thermoplastic elastomercomposition are φ_(m) and φ_(d) and the melt viscosities of thecomponents are η_(m) and η_(d) and further to bring the ratio ofviscosities η_(m)/η_(d) close to 1 to reduce the rubber dispersedparticle size of the domain to improve the durability (Japanese PatentApplication No. 8-193545, Japanese Patent Application No. 9-175150, andJapanese Patent Application No. 10-235386). However, the durability atlow temperatures was insufficient by just reducing the rubber particlesize.

DISCLOSURE OF THE INVENTION

[0007] An object of the present invention is to solve theabove-mentioned problems and to provide a thermoplastic elastomercomposition which is excellent in heat resistance and durability, whilemaintaining the flexibility and to provide the use of the elastomercomposition for the air permeation preventive layer of a tire so that,when the elastomer composition is used as the air permeation preventivelayer of a tire, it gives a tire excellent in heat resistance anddurability, while being excellent in flexibility and, further, does notstick on the shaping bladder and, therefore, is excellent in surfacefinish as well.

[0008] Another object of the present invention is to provide a processfor producing a thermoplastic elastomer composition which is free fromreversal of the dispersed structure of the resin component as thecontinuous phase (matrix) and the rubber component as the dispersionphase (domain) even when the rubber ratio is 50% or more and, further,has the properties of being more flexible, large in strength andelongation as well, and superior in durability.

[0009] A still further object of the present invention is to provide athermoplastic elastomer composition having a structure having a blendedresin as a matrix and a rubber elastomer dispersed therein, wherein notonly the dispersed particle size of the rubber elastomer, but also thestructure of the blended resin of the matrix phase are controlled toimprove the durability, in particular the durability at lowtemperatures, while maintaining the air permeation preventive propertyand a pneumatic tire and hose using that thermoplastic elastomercomposition.

[0010] In accordance with the present invention, there is provided athermoplastic elastomer composition comprising an elastomer componentcontaining a nylon resin having a melting point of 170 to 230° C. and ahalide of an isobutylene-p-methylstyrene copolymer, which is dynamicallyvulcanized to a gelation rate of 50 to 95%.

[0011] In accordance with the present invention, there is provided athermoplastic elastomer composition characterized in that the nylonresin is composed of nylon 11 or nylon 12 and nylon 6/66 copolymer at aratio of 10/90 to 90/10, in that a molecular weight distribution (Mw/Mn)of a blend of the nylon 11 or nylon 12 and the nylon 6/66 copolymer inthe thermoplastic elastomer composition is Mw/Mn<10.0, preferably Mw/Mn<5.0, and in that a cross-linking agent for cross-linking the elastomercomponent is previously mixed into the elastomer component in advance.

[0012] In accordance with the present invention, there is provided apneumatic tire having the above thermoplastic elastomer composition asan air permeation preventive layer.

[0013] In accordance with the present invention, there is furtherprovided a process for producing a thermoplastic elastomer compositioncomprising the steps of mixing a rubber composition (A) and athermoplastic resin (B) under conditions of the following equations (I)and (II):

(φ_(A)/φ_(B))×(η_(B)/η_(A))<1.0   (I)

0.8<(η_(A)/η_(B))<1.2   (II)

[0014] wherein φ_(A): volume fraction of rubber composition (A), φ_(B):volume fraction of resin (B), η_(A): melt viscosity of rubbercomposition (A), η_(B): melt viscosity of resin (B)); and

[0015] mixing the resultant composition (C) and a rubber composition (D)under conditions of the following formulas (III) and (IV):

(φ_(D)/φ_(C))×(η_(C)/η_(D))<1.0   (III)

0.8<(η_(C)/η_(D))<1.2   (IV)

[0016] wherein φ_(D): volume fraction of rubber composition (D), φ_(C):volume fraction of composition (C), η_(D): melt viscosity of rubbercomposition (D), η_(C): melt viscosity of composition (C).

[0017] In accordance with the present invention, there is provided apneumatic tire using a thermoplastic elastomer composition prepared bythe above process of production for an air permeation preventive layerof the tire.

[0018] In accordance with the present invention, there is furtherprovided a thermoplastic elastomer composition comprising an elastomercomposition (A′), as a dispersion phase, and a thermoplastic resincomposition (B′), as a matrix and having said thermoplastic resincomposition composed of a blend of at least two thermoplastic resins,wherein the dispersed particle size of the elastomer composition (A′) isnot more than 10 μm and the particle size of a resin composition (D′)dispersed in a matrix resin composition (C′) in the thermoplastic resincomposition (B′) is smaller than the particle size of the dispersedrubber.

[0019] In accordance with the present invention, there is furtherprovided a thermoplastic elastomer composition, wherein the elastomercomposition (A′) and the thermoplastic resin composition (B′) satisfythe following equations (V) and (VI):

(φ_(d)/φ_(m))×(η_(m)/η_(d))<1.0   (V)

0.8<(η_(m)/η_(d))<1.2   (VI)

[0020] wherein φ_(d): volume fraction of elastomer composition (A′),φ_(m): volume fraction of thermoplastic resin composition (B′), η_(d):melt viscosity of elastomer composition (A′), η_(m): melt viscosity ofthermoplastic resin composition (B′) and

[0021] the matrix resin composition (C′) and dispersed resin composition(D′) in the thermoplastic resin composition (B′) satisfy the followingequations (VII) and (VIII):

(φ_(D′)/φ_(C′))×(η_(C′)/η_(D′))<1.0   (VII)

0.8<(η_(C′)/η_(D′))<1.2   (VIII)

[0022] wherein φ_(D′): volume fraction of dispersed resin composition(D′), φ_(C′): volume fraction of matrix resin composition (C′), η_(D′):melt viscosity of dispersed resin composition (D′), η_(C′): meltviscosity of matrix resin composition (C′).

[0023] Further, in accordance with the present invention, there is aprovided a thermoplastic elastomer composition characterized in that ablend of at least two polyamide resins is selected as the thermoplasticresin composition (B′) and in that a polyamide resin having at leastseven methylene groups with respect to one amide group is contained asthe matrix resin composition (C′) in the thermoplastic resin composition(B′) and a polyamide resin having less than seven methylene groups withrespect to one amide group is contained as the dispersed resincomposition (D′).

[0024] Further, in accordance with the present invention, there isprovided a pneumatic tire and hose using the thermoplastic elastomercomposition obtained according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be explained in further detail belowwith reference to the drawings, wherein:

[0026]FIG. 1 is a view of the microstructure obtained by a micrograph(×3000) of a thermoplastic elastomer composition obtained according toExample II-1 of the present invention.

[0027]FIG. 2 is a view of the microstructure obtained by a micrograph(×3000) of a thermoplastic elastomer composition obtained according toComparative Example II-2.

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] The thermoplastic elastomer composition according to a firstaspect of the present invention includes a composition obtained byblending into a nylon resin having a melting point of 170 to 230° C. anelastomer including a halide of isobutylene-p-methylstyrene copolymer(X-IPMS) and dynamically vulcanizing it to a gelation rate of 50 to 95%.The thermoplastic elastomer composition according to the presentinvention must be composed of the thermoplastic resin component of thenylon resin forming a continuous phase and an elastomer componentincluding the X-IPMS uniformly blended therein as a dispersion phase.Further, the present invention is characterized by the elastomercomponent being present with a gelation rate of 50 to 95%, whereby theheat resistance and the durability—weak points in this type ofthermoplastic elastomer composition in the past—are improved.

[0029] Here, the gelation rate is obtained by extracting a sample a dayand night by a Soxhlet apparatus by a solvent for rubber (in this case,acetone and n-hexane), weighing the dried residue, and applying suitablecorrection based on knowledge regarding the composition so as todetermine the amount of the insoluble polymer. That is, the correctedinitial and final weights are obtained by subtracting from the firstweights the soluble components other than rubber and the organicsolvent-soluble resin component. All insoluble pigments, fillers, etc.are subtracted from the initial and final weights.

[0030] When the gelation rate is less than 50%, even if the rubber andresin are mixed together in a high shear state, the rubber oncedispersed joins together again, it is not possible to disperse and fixthe rubber finely (particle size of several microns) in the resin, andthe film properties deteriorate. Further, when the gelation rate exceeds95%, when the thermoplastic elastomer composition is subjected to adynamic durability test, the Young's modulus of the elastomer componentbecomes too large, and therefore, the composition is destroyed startingat the elastomer. In view of this, it is preferable that the gelationrate is 50 to 95%.

[0031] In the thermoplastic elastomer composition according to thepresent invention, a nylon resin having a melting point of 170 to 230°C. is selected for use as the thermoplastic resin component and a rubbercomponent containing X-IPMS is selected for use as the elastomercomponent. The nylon resin having the melting point of 170 to 230° C.usable in the present invention includes nylon 6 (N6), nylon 11 (N11),nylon 12 (N12), a nylon 6/66 copolymer (N6/66), nylon 610 (N610), andnylon 612 (N612). Further, the rubber component usable together with theX-IPMS of the elastomer component, includes diene rubbers and thehydrates thereof (for example NR, IR, epoxylated natural rubber, SBR, BR(high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR),olefin rubbers (for example, ethylene propylene rubbers (EPDM, EPM),maleic acid-modified ethylene propylene rubbers (M-EPM), IIR,isobutylene and aromatic vinyl or diene monomer copolymers, acrylicrubbers (ACM), ionomers), halogen-containing rubbers (for example,Br-IIR, Cl-IIR, bromide of isobutylene-p-methylstyrene copolymer)(Br-IPMS), chloroprene rubbers (CR), hydrin rubbers (CHR),chlorosulfonated polyethylenes (CSM), chlorinated polyethylenes (CM),maleic acid-modified chlorinated polyethylenes (M-CM)), silicone rubbers(for example, methylvinyl silicone rubbers, dimethyl silicone rubbers,methylphenylvinyl silicone rubbers), sulfur-containing rubbers (forexample, polysulfide rubbers), fluoro rubbers (for example, vinylidenefluoride rubbers, fluorine-containing vinyl ether-based rubbers,tetrafluoroethylene-propylene rubbers, fluorine-containing siliconerubbers, fluorine-containing phosphagen rubbers), thermoplasticelastomers (for example, styrene elastomers, olefin elastomers, esterelastomers, urethane elastomers, or polyamide elastomers), etc. may bementioned.

[0032] In the thermoplastic elastomer composition of the presentinvention, the nylon resin having the above range of melting points wasselected as the thermoplastic resin component because, when those havinga melting point less than 170° C. are used, the thermoplastic elastomercomposition melts at the time of vulcanization of the tire, sticks tothe bladder, and causes the appearance of the tire inside surface todeteriorate, while when those having a melting point of over 230° C. areused, the Young's modulus of the thermoplastic elastomer becomes largeand the durability of the thermoplastic elastomer composition fallsduring tire use. Further, as the rubber component capable of beingcontained in the X-IPMS of the elastomer component, preferably anethylenically unsaturated nitrile-conjugated diene-based high saturationcopolymer rubbers (HNBR), epoxylated natural rubbers (ENR), NBR, hydrinrubbers, acryl rubbers, etc. may be mentioned, but these are used forthe purpose of improving the compatibility of the nylon and X-IPMS whichare largely different in solubilities. In this elastomer component, theX-IPMS serving as the main ingredient is required to be blended in anamount at least 30% by weight of the total amount of the rubbercomponent in order to improve the air permeation preventive property andheat resistance of the thermoplastic elastomer composition. Theremainder may be made the above rubber component jointly used.

[0033] The elastomer component including the X-IPMS may be blended intothe above specific nylon resin in the thermoplastic elastomercomposition of the present invention in a ratio by weight in the rangeof 30/70 to 70/30, preferably in the range of 35/65 to 50/50.

[0034] According to a preferred embodiment of the present invention, thethermoplastic elastomer composition may be formulated using athermoplastic resin component where the nylon resin component iscomposed of nylon 11 (N11) or nylon 12 (N12) and nylon 6/66 copolymer(N6/N66) in a ratio of composition (ratio by weight) of 10/90 to 90/10,preferably 30/70 to 85/15. This thermoplastic elastomer composition isparticularly preferable in the point of providing a thermoplasticelastomer superior in durability and superior in the tire insideappearance and air permeation preventive property and, further, having agood balance of these properties.

[0035] Further, a thermoplastic elastomer composition where themolecular weight distribution (Mw/Mn) of the blend of the N11 or N12 andN6/66 in the thermoplastic elastomer composition is Mw/Mn<10.0,preferably Mw/Mn<5.0, more preferably Mw/Mn<3.0, in terms of themolecular weight distribution according to extraction and measurement ofthe resin after twin-screw mixing gives the thermoplastic elastomercomposition of the present invention superior in fatigue endurance, inaddition to the above properties.

[0036] Cutting of the molecule occurs in the resin component (N11 or N12and N6/66 blend) in the thermoplastic elastomer composition due to thehigh temperature, high shear conditions at the time of twin-screw mixingand the components used for the cross-linking agent of the elastomercomponent (for example, amine vulcanization accelerator, metal halideproduced from a metal oxide and halide). If the molecule is cut, themolecular weight distribution of the resin component tends to becomelarger. If this exceeds 10, it was found that the durability inparticular decreases.

[0037] The elastomer component compounded into the thermoplasticelastomer composition according to the present invention may had addedthereto the compounding agents generally blended into elastomers forimproving the dispersion and heat resistance of the elastomer and thelike, such as a reinforcing agent, filler, cross-linking agent,softening agent, antioxidant, and processing aid. Among these, in thethermoplastic elastomer composition of the present invention, thenecessary amount of cross-linking agent is added into the elastomercomponent, but in order to achieve a gelation rate of 50 to 95% of theelastomer required in the present invention, it is effective to adoptthe method of previously mixing the cross-linking agent capable ofcross-linking the elastomer into the elastomer component. By thismethod, compared with the method as in the past of melt mixing thethermoplastic resin component and the elastomer component, then addingthe cross-linking agent, the cross-linking agent does not partiallyreact with the thermoplastic resin and give much action of cutting ofmolecule etc. to the resin and, further, control of the gelation rate ofthe elastomer component is easy. As a result, there is littledeterioration of the thermoplastic resin, vulcanization of 50 to 95% ofthe elastomer component is achieved, and the durability of thethermoplastic elastomer composition of the present invention can beenhanced.

[0038] The process for producing of the thermoplastic elastomercomposition of the present invention can be performed by the followingprocedure.

[0039] First, a general kneader, Bambury mixer, etc. is previously usedto mix the elastomer component and predetermined cross-linking agentuntil a uniform mixed state is obtained. At this time, the elastomercomponent may have added thereto suitable amounts of fillers such ascarbon, oil, and also calcium carbonate. Further, during the mixing, ifthe temperature of the material is too high, the rubber component wouldcause a cross-linking reaction in the kneader or mixer, and therefore,the temperature has to be suppressed to a low temperature of not morethan 120° C. during the mixing.

[0040] The cross-linking agent-containing elastomer component thusprepared and predetermined nylon resin are charged into a twin-screwmixing extruder etc. The rubber component is made to dynamicallycross-link, while performing the melt mixing to cause the elastomercomponent to disperse as a dispersion phase (domain) in the nylon resinforming the continuous phase (matrix phase).

[0041] Further, various compounding agents (except the vulcanizationagents) may be added to the nylon resin or elastomer component duringthe above mixing, but it is preferable to mix them in advance before themixing. The mixer used for the mixing of the nylon resin and elastomercomponent is not particularly limited, but a screw extruder, kneader,Bambury mixer, twin-screw mixing extruder, etc. may be used. Amongthese, a twin-screw mixing extruder is preferably used for mixing of thenylon resin and elastomer component and dynamic vulcanization of theelastomer component. Further, two or more types of mixers may be usedfor successive mixing. As the conditions for the melt mixing, thetemperature should be at least the temperature at which thepredetermined nylon resin melts. Further, the shear rate at the time ofmixing is preferably 500 to 7500 sec⁻¹. The overall time of the mixingis preferably from 30 seconds to 10 minutes.

[0042] The thermoplastic elastomer composition thus obtained isstructured with the elastomer component forming a discontinuous phasedispersed as a dispersion phase (domain) in a matrix of the nylon resinforming the continuous phase. By adopting such a state of dispersionstructure, thermoplastic processing becomes possible and the sameshaping processability as with a nylon resin can be obtained at the timeof shaping, and therefore, a film can be formed by an ordinary moldingmachine for resin, that is, by extrusion or calendaring.

[0043] As the vulcanization agent previously blended into the elastomercomponent, a general rubber vulcanization agent (i.e., cross-linkingagent) may be used. Specifically, as a sulfur vulcanization agent,powdered sulfur, precipitated sulfur, high dispersion sulfur,surface-treated sulfur, insoluble sulfur, dimorpholinedisulfide,alkylphenoldisulfide, etc. may be mentioned. For example, they may beused in an amount of about 0.5 to 4 phr (parts by weight per 100 partsby weight of the elastomer component (polymer)).

[0044] Further, as an organic peroxide vulcanization agent,benzoylperoxide, t-butylhydroperoxide, 2,4-dichlorobenzoylperoxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethylhexane-2,5-di(peroxylbenzoate), etc. may be mentioned. Forexample, 1 to 20 phr or so may be used.

[0045] Further, as a phenol resin vulcanization agent, a bromide of analkylphenol resin or a mixed cross-linking agent system containingstannous chloride, chloroprene, or other halogen donor and analkylphenol resin may be mentioned. For example, 1 to 20 phr or so maybe used.

[0046] In addition, zinc oxide (5 phr or so), magnesium oxide (4 phr orso), lyserge (10 to 20 phr or so), p-quinonedioxime,p-dibenzoylquinonedioxime, tetrachloro-p-benzoquinone,poly-p-dinitrosobenzene (2 to 10 phr or so), and methylenedianiline (0.2to 10 phr or so) may be exemplified.

[0047] Further, if necessary, a vulcanization accelerator may be addedto the vulcanization agent. As the vulcanization accelerator, generalvulcanization accelerator such as an aldehyde-ammonia, guanidine,thiazole, sulfenamide, thiuram, dithio acid salt, thiurea, may be added,for example, in an amount of 0.5 to 2 phr or so.

[0048] The thermoplastic elastomer composition according to the presentinvention is superior in heat resistance and durability as well, whilebeing superior in flexibility, is free from sticking to the bladder forvulcanization use and is low in air permeability, and therefore,superior in air permeation preventive property as well, and therefore,can be effectively used for the air barrier layer in a tire.

[0049] In the second aspect of the present invention, the fact was foundthat, in the production of a thermoplastic elastomer compositionstructured with a thermoplastic resin component as a continuous phase(matrix) and a rubber component as a dispersion phase (domain), if thecomponents are mixed and vulcanized by a two-stage mixing process withthe ratio of the melt viscosities of the components at the individualmixing stages and the volume fractions×ratio of melt viscosities keptunder certain conditions, it is possible to maintain the dispersionstructure even in a range where the ratio of compounded rubber exceeds50% by weight and the rubber dispersed particle size of the domainbecomes extremely small, whereby a thermoplastic elastomer compositionwhich is flexible, large in strength and elongation as well, andsuperior in durability as well is obtained.

[0050] Further, in the present invention, in the production of thethermoplastic elastomer composition, in the first stage of the mixingprocess, the rubber composition (A) and resin (B) are selected such thatthe ratio of the melt viscosities of the rubber composition (A)/resin(B) becomes 0.8 to 1.2 and the equation

(φ_(A)/φ_(B))×(η_(B)/η_(A))< 1. 0

[0051] wherein φ_(A): volume fraction of rubber composition (A), φ_(B):volume fraction of resin (B), η_(A): melt viscosity of rubbercomposition (A), η_(B): melt viscosity of resin (B) are mixed to firstproduce the composition (C), then suitably thereafter a second stage ofthe mixing process is performed to mix a rubber composition (D) and theabove obtained composition (C) so that the ratio of the melt viscositiesof the rubber composition (D)/composition (C) becomes 0.8 to 1.2 and theequation

(φ_(D)/φ_(C))×(η_(C)/η_(D))<1.0

[0052] wherein φ_(D): volume fraction of rubber composition (D), φ_(C):volume fraction of composition (C), η_(D): melt viscosity of rubbercomposition (D), η_(C): melt viscosity of composition (C), whereby athermoplastic elastomer composition which is flexible, high in strength,high in elongation, and superior in durability can be obtained

[0053] The rubber composition (A) usable in the production of thethermoplastic elastomer composition of the present invention may be madea rubber composition composed of a rubber component into which ordinaryrubber formulation components including vulcanization system componentsare blended or may be made a rubber composition comprising a rubbercomponent into which the ordinary rubber formulation components otherthan the vulcanization ingredients are blended. As the rubber component,diene rubbers such as natural rubbers, synthetic polyisoprene rubbers(IR), epoxylated natural rubbers, styrene-butadiene rubbers (SBR),polybutadiene rubbers (BR), nitrile-butadiene rubbers (NBR),hydrogenated NBR, and hydrogenated SBR and their hydrogenates; olefinrubbers such as ethylene propylene rubber (EPDM, EPM), a maleicacid-modified ethylene propylene rubber (M-EPM), butyl rubber (IIR), anisobutylene and aromatic vinyl or diene-based monomer copolymer, anacrylic rubber (ACM), ionomer, a halogen-containing rubber (Br-IIR,Cl-IIR, a bromide of an isobutylene-p-methylstyrene copolymer (Br-IPMS),chloroprene rubber (CR), a hydrin rubber (CHC, CHR), chlorosulfonatedpolyethylene (CSM), chlorinated polyethylene (CM), and maleicacid-modified chlorinated polyethylene (M-CM)); a silicone rubber suchas a methylvinyl silicone rubber, dimethyl silicone rubber, ormethylphenylvinyl silicone rubber; a sulfur-containing rubber such as apolysulfide rubber; a fluororubber such as a vinylidene fluoride rubber,fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylenerubber, fluorine-containing silicone rubber, or fluorine-containingphosphagen rubber; a thermoplastic elastomer such as a styreneelastomer, olefin elastomer, polyester elastomer, urethane elastomer, orpolyamide elastomer, etc. may be mentioned.

[0054] When using a rubber composition comprising a rubber ingredientnot including the vulcanization formulation components, it is preferableto blend in the vulcanization system after the first stage of the mixingprocess.

[0055] As the resin (B) usable for the production of the thermoplasticelastomer composition of the present invention, a thermoplastic resin isused. As the resin ingredient, an olefin resin (for example,homopolypropylene, block polypropylene, random polypropylene, highmolecular weight polyethylene, low molecular weight polyethylene,α-olefin-ethylene copolymer), polyamide-based resin (for example, nylon6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12),nylon 610 (N610), nylon 612 (N612), nylon 6/66 copolymer (N6/66), nylon6/66/610 copolymer (N6/66/610), nylon MXD6 (MXD6), nylon 6T, nylon 6/6Tcopolymer, nylon 66/PP copolymer, and nylon 66/PPS copolymer), apolyester-based resin (for example, polybutylene terephthalate (PBT),polyethylene terephthalate (PET), polyethylene isophthalate (PEI),PET/PEI copolymer, polyacrylate (PAR), polybutylenenaphthalate (PBN),liquid crystal polyester, polyoxyalkylenediimidate/polybutyrateterephthalate copolymer, and other aromatic polyesters), apolynitrile-based resin (for example, polyacrylonitrile (PAN),polymethacrylonitrile, acrylonitrile/styrene copolymer (AS),methacrylonitrile/styrene copolymer, methacrylonitrile/styrene/butadienecopolymer), a polymethacrylate-based resin (for example, polymethylmethacrylate (PMMA) and polyethyl methacrylate), a polyvinyl-based resin(for example, vinyl acetate (EVA), polyvinylalcohol (PVA),vinylalcohol/ethylene copolymer (EVOH), polyvinylidene chloride (PVDC),polyvinyl chloride (PVC), vinyl chloride/vinylidene chloride copolymer,and vinylidene chloride/methylacrylate copolymer), a cellulose resin(for example, cellulose acetate, cellulose acetate butyrate), afluororesin (for example, polyvinylidene fluoride (PVDF), polyvinylfluoride (PVF), polychlorofluoroethylene (PCTFE), andtetrachloroethylene/ethylene copolymer (ETFE)), an imide resin (forexample, aromatic polyimide (PI)), etc. may be mentioned.

[0056] As the rubber composition (D) usable for the production of thethermoplastic elastomer composition of the present invention, it ispossible to use a rubber composition obtained by blending, into therubber component ordinary rubber, compounding agents including thevulcanization system formulation components or a rubber compositionobtained by blending into the rubber component ordinary rubbercompounding agents excluding the vulcanization system formulationcomponents. When not including the vulcanization system formulationcomponents in the rubber component, the vulcanization system formulationcomponents are blended after the second stage of the mixing process.Further, the various thermoplastic elastomers listed above are used forthe rubber component mixed with the rubber composition (D).

[0057] As the vulcanization agent used for the rubber component, ageneral rubber vulcanization agent (cross-linking agent) may be used.Specifically, as a sulfur vulcanization agent, powdered sulfur,precipitated sulfur, high dispersion sulfur, surface-treated sulfur,insoluble sulfur, dimorpholinedisulfide, alkylphenoldisulfide, etc. maybe mentioned. For example, they may be used in amounts of about 0.5 to 4phr (parts by weight per 100 parts by weight of the rubber component(polymer).

[0058] Further, as an organic peroxide vulcanization agent,benzoylperoxide, t-butylhydroperoxide, 2,4-dichlorobenzoylperoxide,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethylhexane-2,5-di(peroxylbenzoate), etc. may be mentioned. Forexample, 1 to 20 phr or so may be used.

[0059] Further, as a phenol resin vulcanization agent, a bromide of analkylphenol resin or a mixed cross-linking agent containing such asstannous chloride, chloroprene, halogen donor and an alkylphenol resinmay be mentioned. For example 1 to 20 phr or so may be used.

[0060] In addition, zinc oxide (about 5 phr), magnesium oxide (4 phr orso), lyserge (about 10 to 20 phr), p-quinonedioxime,p-dibenzoylquinonedioxime, tetrachloro-p-benzoquinone,poly-p-dinitrosobenzene (about 2 to 10 phr or so), andmethylenedianiline (0.2 to 10 phr) may be exemplified.

[0061] Further, if necessary, a vulcanization accelerator may be addedto the vulcanization agent. As the vulcanization accelerator, generalvulcanization accelerators such as an aldehyde-ammonia, guanidine,thiazole, sulfenamide, thiuram, dithio acid salt, thiurea may be addedfor example in about 0.5 to 2 phr.

[0062] The process for producing the thermoplastic elastomer compositionof the present invention can be performed, for example, by the followingprocedure.

[0063] First, a general kneader, Bambury mixer, etc. is previously usedto mix the predetermined rubber component and predeterminedcross-linking agent until a uniform mixed state is obtained so as toprepare the rubber compositions (A) and (D). At this time, the rubbercompositions may have added to them suitable amounts of fillers such ascarbon, oil, and also calcium carbonate.

[0064] The rubber composition (A) thus prepared and predetermined resin(B) are charged into a twin-screw mixing extruder etc. used for thefirst mixing process for the melt mixing. In the case of use of a rubbercomposition composed of the rubber composition (A), without thevulcanization compounding agents, the vulcanization compounding agentsare added at the stage where mixing has been sufficiently performed,then further mixing is continued to cause the rubber composition todynamically cross-link to give a composition (C) of a structure with therubber composition dispersed as a dispersion phase (domain) in the resinforming the continuous phase (matrix). Suitably, thereafter, thecomposition (C) is taken out, then is led to a twin-screw mixingextruder used for the second kneading process, where the rubbercomposition (D) is added and mixing performed. When using a rubbercomposition comprising the rubber composition (D), without thevulcanization compounding agents, the vulcanization compounding agentsare added at the stage when the mixing has been sufficiently performed,then the mixing is continued to dynamically cross-link the rubbercomposition. By performing this two-stage mixing operation in this way,a thermoplastic elastomer composition having a domain of extremely smallrubber particles dispersed in a resin matrix in a state having a highrubber ratio is obtained.

[0065] Further, in the production of the above thermoplastic elastomercomposition, two twin-screw mixing extruders were used, but it is alsopossible to obtain the desired thermoplastic elastomer composition bythe method of using a single twin-screw mixing extruder. In this case,the rubber composition (A) and resin (B) are added and mixed in thefront of the twin-screw mixing extruder, then the vulcanization systemcomponents are added and mixed, then the rubber composition (D) is addedand mixed at the rear of the twin-screw mixing extruder, whereby athermoplastic elastomer composition having the same type of dispersionstructure as the above is obtained.

[0066] Further, the various compounding agents (except vulcanizationformulation components) may be added to the thermoplastic resin orrubber composition during the above mixing, but they may also bepreviously mixed before the mixing. The mixer used for the mixing of therubber composition (A) and resin (B) and further the mixing of thecomposition (C) of the mixed matter and the rubber composition (D) isnot particularly limited. A screw extruder, kneader, Bambury mixer,twin-screw mixing extruder, etc. may be used. Among these, use of atwin-screw mixing extruder is preferable for mixing of the resin andrubber component and dynamic vulcanization of the rubber component. Asthe conditions for the melt mixing, the temperature should be at leastthe temperature at which the thermoplastic resin melts. Further, theshear rate at the time of mixing is preferably 500 to 7500 sec⁻¹. Theoverall time of the mixing is preferably from 30 seconds to 10 minutes.

[0067] The thermoplastic elastomer composition obtained in this way isstructured with an extremely fine-particle-sized rubber componentforming a discontinuous phase dispersed as a dispersion phase (domain)in a matrix of the thermoplastic resin forming the continuous phase. Byadopting such a state of a dispersion structure, thermoplasticprocessing becomes possible and the same shapability as with athermoplastic resin can be obtained at the time of molding, andtherefore, a film can be formed by an ordinary resin-use moldingmachine, that is, by extrusion, calendaring, or injection molding.

[0068] When the solubilities of the thermoplastic resin and rubbercomposition differ, it is preferable to add as a third component asuitable compatibilizer. By mixing a compatibilizer into the system, thesurface tension between the thermoplastic resin and the rubbercomposition is decreased and, as a result, the particle size of therubber composition forming the dispersion phase will become finer, andtherefore, the properties of the two components will be more effectivelyexpressed. As such a compatibilizer, generally it is possible to use acopolymer having the structure or both or one of the thermoplastic resinand rubber polymer or a structure of a copolymer having an epoxy group,carbonyl group, halogen group, amine group, oxazoline group, hydroxygroup, etc. capable of reacting with the thermoplastic resin or rubberpolymer. These may be selected based upon the type of the thermoplasticresin polymer and rubber polymer to be mixed, but as those which arenormally used, a styrene/ethylene-butylene block copolymer (SEBS) andits maleic acid-modified form, EPDM: EPDM/styrene, or EPDM/acrylonitrilegraft copolymer and their maleic acid-modified forms, styrene/maleicacid copolymer, reactive phenoxy thermoplastic resin, etc. may bementioned. The amount of the compatibilizer blended is not particularlylimited, but preferably is 0.5 to 10 parts by weight, based upon 100parts by weight of the polymer component (total of the thermoplasticresin polymer and rubber polymer).

[0069] Since the thermoplastic elastomer composition obtained by theproduction process of the present invention has the above dispersedstructure, it is extremely flexible and high in strength and elongationand is superior in durability as well. Further, the film when formedinto a film is extremely superior in air barrier property, andthorefore, it is possible to effectively use the thin film as an innerliner layer of a pneumatic tire.

[0070] According to the third aspect of the present invention, it wasfound that by controlling the dispersed particles of the rubberelastomer to become smaller than a predetermined particle size andcontrolling the particle size of the dispersed resin particles in thematrix phase to become smaller than the particle size of the rubberelastomer dispersed particles in a thermoplastic elastomer compositionhaving a structure of a blended resin as a matrix and a rubber elastomerdispersed in it, it is possible to greatly improve the durability, inparticular the compression set at low temperatures.

[0071] In a thermoplastic elastomer composition according to the presentinvention composed of the elastomer composition (A′) as the dispersionphase and the thermoplastic resin composition (B′) as the matrix andwith the thermoplastic resin composition composed of a blend of at leasttwo thermoplastic resins, the fact that the dispersed particle size ofthe elastomer composition (A′) is not more than 10 μm, preferably notmore than 5 μm, and the particle size of the resin composition (D′)dispersed in the matrix resin composition (C′) in the thermoplasticresin composition (B′) is smaller than the dispersed rubber particlesize are necessary not only for improving the durability at the time ofheat and at the time of ordinary temperature, in particular, thedurability when considering the state of use at stringent conditions at10° C., 0° C., −20° C., or −40° C.

[0072] To achieve this phase structure of the present invention, first,the ratio of the volume fractions and the ratio of the melt viscositiesof the elastomer composition (A′) and the thermoplastic resincomposition (B′) are controlled so that the elastomer composition (A′)and thermoplastic resin composition (B′) satisfy the following equations(V) and (VI):

(φ_(d)/φ_(m))×(η_(m)/η_(d))<1.0   (V)

0.8<(η_(m)/η_(d))<1.2   (VI)

[0073] wherein φ_(d): volume fraction of elastomer composition (A′),φ_(m): volume fraction of thermoplastic resin composition (B′), η_(d):melt viscosity of elastomer composition (A′), η_(m): melt viscosity ofthermoplastic resin composition (B′).

[0074] Second, the ratio of the volume fractions and the ratio of themelt viscosities of the matrix resin composition (C′) and dispersedresin composition (D′) in the thermoplastic resin composition (B′)should be controlled so that the matrix resin composition (C′) anddispersed resin composition (D′) satisfy the following equations (VII)and (VIII):

(φ_(D′)/φ_(C′))×(η_(C′)/η_(D′))<1.0   (VII)

0.8<(η_(C′)/η_(D′))<1.2   (VIII)

[0075] wherein φ_(D′): volume fraction of dispersed resin composition(D′), φ_(C′): volume fraction of matrix resin composition (C′), η_(D′):melt viscosity of dispersed resin composition (D′), η_(C′): meltviscosity of matrix resin composition (C′).

[0076] In the present invention, by controlling the composition so as tosatisfy the above formulae (V) and (VI), the rubber elastomer componentforms the dispersion phase and the thermoplastic resin component formsthe continuous phase and the rubber elastomer dispersion phase becomes amicrodispersion phase. Further, by controlling the composition so as tosatisfy the above formulae (VII) and (VIII), a dispersed resin phase isformed in the matrix resin of the continuous phase and the resindispersion phase becomes a microdispersion phase to give a thermoplasticelastomer composition remarkably improved in durability at lowtemperature.

[0077] The rubber elastomer composition (A′) usable for the productionof the thermoplastic elastomer composition of the present invention maybe made a rubber elastomer composition composed of a rubber elastomercomponent in which is blended ordinary rubber compounding agentsincluding the vulcanization formulation components or a rubber elastomercomposition composed of the rubber elastomer component in which isblended ordinary rubber compounding agents not including thevulcanization formulation components. As the rubber elastomer component,one the same as the rubber component in the above second aspect may beused.

[0078] The vulcanization agent, vulcanization aid, vulcanizationconditions (temperature, time), etc. when dynamically vulcanizing therubber elastomer component constituting the dispersion phase of thethermoplastic elastomer composition of the present invention may besuitably determined depending upon the composition of the rubberelastomer component added and are not particularly limited.

[0079] As the vulcanization agent, a general rubber vulcanization agent(cross-linking agent) may be used. Specifically, as a sulfurvulcanization agent, powdered sulfur, precipitated sulfur, highdispersion sulfur, surface treated sulfur, insoluble sulfur,dimorpholinedisulfide, alkylphenoldisulfide, etc. may be mentioned. Forexample, they may be used in amounts of about 0.5 to 4 phr (parts byweight per 100 parts by weight of the elastomer component (polymer)).

[0080] Further, the organic peroxide vulcanization agent, phenol resinvulcanization agent, and other ingredients are the same as in the abovesecond aspect. The amounts of formulation are also the same as explainedabove.

[0081] Further, in accordance with need, a vulcanization accelerator maybe added. As the vulcanization accelerator, vulcanization acceleratorssuch as an aldehyde-ammonia, guanidine, thiazole, sulfenamide, thiuram,dithio acid salt, thiurea may be added in an amount of, for example, 0.5to 2 phr or so. Further, as the vulcanization acceleration aid, ageneral rubber aid may be used at the same time. For example, stearicacid or oleic acid and their Zn salts (2 to 4 phr or so) etc. may beused in the same way as in the above second aspect.

[0082] Further, the rubber elastomer forming the dispersion phase may,if necessary, have suitably blended into it, in addition to the abovecompounding agents, a softening agent, antioxidant, processing aid, orother compounding agent for improving the dispersion, heat resistance,etc.

[0083] Further, as the thermoplastic resin composition (B′) usable forthe production of the thermoplastic elastomer composition of the presentinvention, a blend of at least two thermoplastic resins is used. As theresin ingredient, a polyamide resin (for example, nylon 6 (N6), nylon 66(N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610),nylon 612 (N612), nylon 6/66 copolymer (N6/66), nylon 6/66/610 copolymer(N6/66/610), nylon MXD6 (MXD6), nylon 6T, nylon 6/6T copolymer, nylon66/PP copolymer, and nylon 66/PPS copolymer), a polyester resin (forexample, polybutylene terephthalate (PBT), polyethylene terephthalate(PET), polyethylene isophthalate (PEI), PET/PEI copolymer, polyacrylate(PAR), polybutylenenaphthalate (PBN), liquid crystal polyester,polyoxyalkylenediimidate/polybutyrateterephthalate copolymer, and otheraromatic polyesters), a polynitrile resin (for example,polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile/styrenecopolymer (AS), methacrylonitrile/styrene copolymer,methacrylonitrile/styrene/butadiene copolymer), a polymethacrylate-basedresin (for example, polymethyl methacrylate (PMMA) and polyethylmethacrylate), a polyvinyl resin (for example, vinyl acetate (EVA),polyvinylalcohol (PVA), vinylalcohol/ethylene copolymer (EVOH),polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinylchloride/vinylidene chloride copolymer, and vinylidenechloride/methylacrylate copolymer), a cellulose resin (for example,cellulose acetate, cellulose acetate butyrate), a fluororesin (forexample, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF),polychlorofluoroethylene (PCTFE), and tetrafluoroethylene/ethylenecopolymer (ETFE)), an imide resin (for example, aromatic polyimide(PI)), etc. may be mentioned.

[0084] As the thermoplastic resin composition (B′) of the presentinvention, a blend of at least two polyamide-based resins mentionedabove is used. Further, among these, a polyamide resin having at leastseven methylene groups with respect to one amide group for the matrixresin composition (C′) in the thermoplastic resin composition (B′) and apolyamide resin having less than seven methylene groups with respect toone amide group for the dispersed resin composition (D′) is morepreferably used for improving the balance of the durability and the gasbarrier property.

[0085] The definitions and numbers of methylene groups with respect tothe amide groups in the above polyamide resins are explained withreference to Table A. TABLE A (Number of Amide Groups vs. MethyleneGroups)

[0086] The thermoplastic resin comprising the matrix of the abovethermoplastic elastomer composition may had added thereto thecompounding agents generally blended for improving the processability,dispersion, heat resistance, anti-oxidation, etc., such as aplasticizer, softening agent, filler, reinforcing agent, processing aid,stabilizer, and antioxidant.

[0087] The production process of the thermoplastic elastomer compositionof the present invention comprising the matrix resin in which theelastomer and synthetic resin are finely dispersed is as follows. First,a general kneader, Bambury mixer, etc. is used to previously mix theelastomer component and compounding agent component until a uniformmixed state is obtained so as to prepare the elastomer composition (A′).At this time, the elastomer component may have added thereto suitableamounts of carbon black, oil, and also calcium carbonate and otherfillers. Further, if necessary, an elastomer vulcanization agent orcross-linking agent, vulcanization aid, vulcanization accelerator, etc.may be added.

[0088] The elastomer component thus prepared and matrix resincomposition (C′) and dispersed resin composition (D′) are charged into atwin-screw mixing extruder etc. for melt mixing. When using an elastomercomposition composed of the elastomer composition (A′) not including thevulcanization compounding agents, the vulcanization compounding agentsare added at the stage when the mixing is sufficiently performed andthen further mixing is performed to cause the elastomer composition todynamically cross-link so as to obtain the desired thermoplasticelastomer composition.

[0089] Further, the various compounding agents may be mixed previouslyin the thermoplastic resin or elastomer composition before the abovetwin-screw mixing, but it is also possible to add them during the abovetwin-screw mixing. As the conditions for the mixing of the elastomercomposition (A′), matrix resin composition (C′), and dispersed resincomposition (D′) and the melt mixing for the dynamic vulcanization ofthe elastomer composition, the temperature should be at least thetemperature at which the thermoplastic resin melts. Further, the shearrate at the time of mixing is preferably 500 to 7500 sec⁻¹. The mixingtime is preferably from 30 seconds to 10 minutes.

[0090] By molding the thermoplastic elastomer composition obtained intoa sheet, film, or tube using a T-sheeting die, straight or crossheadstructure tubing die, inflation molding cylindrical die, etc. at the endof the single-screw extruder, it is possible to use as the airpermeation preventive layer of the pneumatic tire and the rubber/resinlaminate of a hose etc. Note that the thermoplastic elastomercomposition obtained may be taken up into strands once, pelletized, thenmolded by the above single-screw extruder for resin.

[0091] The sheet or tubular molded article thus obtained is composed ofa thermoplastic elastomer composition controlling the morphology of thethree-way blended rubber elastomer/matrix resin/dispersion phase resinof the present invention having a phase structure of vulcanized rubberfinely dispersed in a matrix resin and dispersion phase resin finer thanthe rubber particles dispersed uniformly, and therefore, a thin film hasthe property of a high durability at low temperatures. By making theresin finely dispersed in the matrix resin one superior in gaspermeation preventive property, it is possible to give durability at alow temperature and give superior gas barrier property, and therefore,this can be effectively used for the air permeation preventive layer ofa pneumatic tire or the hose tube or hose cover of a low gas permeablehose.

EXAMPLES

[0092] The present invention will be explained in further detail belowwith reference to the Examples, but the present invention is of coursenot limited in scope to these Examples.

Examples I-1 to I-6 and Comparative Examples I-1 to I-5

[0093] The following commercially available products were used for thecomponents used in the Examples.

[0094] 1) Resin Component

[0095] N11 (nylon 11): Rilsan BMN O (made by Atochem)

[0096] N6/66¹) (nylon 6/66 copolymer): Amilan CM6001 (made by Toray)

[0097] N6/66²) (nylon 6/66 copolymer): Amilan CM6041 (made by Toray)

[0098] N66 (nylon 66): Amilan CM3001N (made by Toray)

[0099] PP (polypropylene): RV421 (made by Tokuyama)

[0100] MAH-g-EEA (maleic acid-modified ethylene ethyl acrylate):A1600(made by Nippon Petrochemicals)

[0101] 2) Rubber (Elastomer) Component

[0102] Br-IPMS: EXXPRO 89-4 (made by Exxon Chemical)

[0103] HNBR: Zetpol 1020 (made by Nippon Zeon)

[0104] ENR: 50% epoxidized natural rubber (made by Malaysia)

[0105] 3) Vulcanization System Components

[0106] zinc oxide: zinc White No. 3 (made by Seido Chemical)

[0107] Zinc stearate: (made by Seido Chemical)

[0108] Stearic acid: Beads Stearate NY (made by NOF Corporation)

[0109] Sulfur: Powdered sulfur (made by Karuizawa Refinery)

[0110] TT: Noccelar TT (made by Ouchi Shinko Chemical)

[0111] M: Noccelar M (made by Ouchi Shinko Chemical)

Production of Thermoplastic Elastomer Composition

[0112] In each of Examples I-1 to I-5 and Comparative Examples I-1 andI-3 to I-5, the predetermined elastomer component and vulcanizationsystem were charged into a Bambury mixer in the formulation shown inTable I-1, mixed for approximately 2 minutes, and dump out at 120° C. toprepare an elastomer component with a vulcanization system. This wasthen pelletized by a rubber pelletizer. Next, the elastomer componentand resin were dry blended in a predetermined formulation, charged intoa twin-screw mixing extruder, and dynamically vulcanized to prepare athermoplastic elastomer composition. The mixing conditions at this timewere a temperature of 230° C. (270° C. in Comparative Example I-4) and ashear rate of 1000 s⁻¹.

[0113] In Example I-6, the elastomer component and resin were melted todispersed with each other, then the vulcanization system was added.

[0114] The thermoplastic elastomer composition prepared by thetwin-screw mixing extruder was water-cooled, then pelletized, thenpassed through a T-die by a single-screw extruder to form it into a filmof a width of 350 mm and thickness of 100 μm.

[0115] The test methods and evaluation methods used in the followingexamples were as follows:

[0116] 1) Test Method of Young's Modulus of Film

[0117] This was based on JIS K6251 “Tensile Test Method of VulcanizedRubber”.

[0118] Test piece: Film samples prepared in the Examples were punchedout into JIS No. 3 dumbbell shapes in parallel to the direction ofextrusion at the time of extrusion of the film.

[0119] A tangent was drawn to the curve of the initial strain region ofthe obtained stress-strain curve and the Young's modulus found from theinclination of the tangent.

[0120] 2) Test Method of Film Air Permeation Coefficient

[0121] Based on JIS K7126 “Air Permeation Test Method of Plastic Filmand Sheets (Method A)”.

[0122] Test pieces: Film samples prepared in Examples were used.

[0123] Test gas: Air (N₂:O₂=8:2)

[0124] Test temperature: 30° C.

[0125] 3) Test Method of 40% Constant Strain Durability

[0126] Rubber-based cement of the formulation shown below was brushed ona thermoplastic elastomer composition film and dried. The film was thensuperposed on tire carcass use rubber (no carcass) of the formulationshown below, then the assembly was vulcanized at 180° C. for 10 minutesto prepare a 2 mm thick film/rubber laminate. This was punched out to aJIS No. 2 dumbbell shape which was used for a durability test at a cycleof 5 Hz while applying 40% constant strain. (Note: the test was stoppedfor samples not breaking after 5,000,000 times.)

Formulation of Rubber-Based Cement

[0127] Parts by Component weight Natural rubber (RSS#3) 80 SBR (Nipol1502, Nippon Zeon) 20 FEF carbon black (HTC#100, Chubu Carbon) 50Stearic acid (Beads Stearic Acid NY, NOF 2 Corporation) ZnO (No. 3 ZincWhite) 3 Sulfur (Powdered Sulfur, Karuizawa 3 Refinery) Vulcanizationaccelerator (BBS, N-t-butyl- 1 2-benzothiazyl sulfenamide) Aromatic oil(Desorex No. 3, Showa Shell 2 Oil) Hexamethoxymethylated melamine(CYREZ- 5 964RPC, Mitsui Cytec) Resorcin-formaldehyde resin (Penacolite10 Resin B-18-S, Indospec Chemical) Phenol-formaldehyde resin (Hitanol1502Z, 1 Hitachi Kasei Kogyo) Toluene 1000

Tire Use Carcass Rubber Formulation

[0128] Parts by Component weight Natural rubber (RSS#3) 80  SBR (Nipol1502, Nippon Zeon) 20  FEF carbon black (HTC#100, Chubu Carbon) 50 Stearic acid (Beads Stearic Acid NY, NOF 2 Corporation) ZnO (No. 3 ZincWhite) 3 Sulfur (Powdered Sulfur, Karuizawa 3 Refinery) Vulcanizationaccelerator (BBS, N-t-butyl- 1 2-benzothiazyl sulfenamide) Aromatic oil(Desorex No. 3, Showa Shell 2 Oil)

[0129] 4) Measurement of Gelation Rate

[0130] The thermoplastic elastomer composition pelletized after thetwin-screw mixing was extracted by a Soxhlet apparatus in a water bathfor 8 hours by acetone. The residue was extracted to a Soxhlet apparatusfor 8 hours by n-hexane. Due to the operation, the unvulcanizedelastomer component was extracted with a solvent. The acetone andn-hexane extracts were dried of their solvents and measured for weight,then the gelation rate was determined by the following equation. (Note:the stearic acid was subtracted since it was extracted with thesolvent.)

[0131] Gelation rate=[[Total amount of elastomer− {(amount of acetoneextracted+amount of n-hexane extracted)−amount of stearic acid}]/(totalamount of elastomer)]×100

[0132] 5) Measurement of Molecular Weight Distribution (Mw/Mn)

[0133] The above n-hexane extraction residue was extracted by a Soxhletapparatus with hexafluoroisoproponol (hereinafter referred to as “HFIP”)for 8 hours. The thermoplastic resin (nylon) was dissolved and extractedby this operation. The extract was acetylated by anhydroustrifluoroacetic acid and measured for molecular weight by GPC. Themolecular weight distribution (Mw/Mn) was found from a comparison of theweight average molecular weight and number average molecular weightusing the data obtained.

[0134] 6) Formation of Tire

[0135] A rubber-based cement of the formulation shown in the test methodof the 40% constant strain durability test of the above 3) was coated ona thermoplastic elastomer film of a width of 350 mm, the film waswrapped over a tire shaping drum, then tire members such as a carcass,side belt, tread were superposed and the assembly inflated to obtain agreen tire. The green tire was vulcanized by a vulcanizer at 180° C. for10 minutes to produce a finished tire of a tire size 165SR13.

[0136] 7) Tire Inside Appearance

[0137] With compositions with low heat resistance, after tirevulcanization, the film partially sticks to the vulcanization bladder orthe surface layer breaks and becomes rough. These are rated as failing(“poor”). Further, compositions where there is no effect on tireperformance, but where the product value is lowered are rated as “fair”.Compositions without such abnormalities are rated as passing (“good”).

[0138] 8) Test Method of Tire Air Leakage Performance

[0139] A 165SR13 steel radial tire (rim 13×4½-J) was used and allowed tostand at an initial pressure of 220 kPa and no-load conditions at roomtemperature of 21° C. for three months and then measured for pressure atmeasurement intervals of every four days.

[0140] The value α was found by recurrence to the function

P _(t) /P ₀ =exp(−αt)

[0141] where the test pressure is P_(t). the initial pressure is P₀, andthe elapsed days is t. The α obtained was used and t=30 substituted intothe following formula to obtain the value β:

β=[1−exp(−αt)]×100

[0142] This value β was used as the rate of pressure loss (%/month) permonth.

[0143] 9) Test Method of Tire Durability

[0144] A 165SR13 steel radial tire (rim 13×4½-J) was used and run on anactual road for 10,000 km at an air pressure of 140 kPa given a load of5.5 kN.

[0145] After being run on, the tire was detached from the rim and theliner layer of the inside surface of the tire was examined visually.Tires with fissures, cracks, visible wrinkles, or peeling or rising ofthe liner layer in the inner layer were rated as failing (“poor”), whiletires without them were rated as passing (“good”). Further, tires withpeeling or rising of the liner, but no fissures or cracks in the linerlayer were rated as (“fair”).

[0146] The test results of the Examples are shown in Table I-1. TABLEI-1 Ex. I-1 Ex. I-2 Ex. I-3 Ex. I-4 Ex. I-5 <Resin> N11 8 16 32 24 24N6/66¹) 32 24 8 16 11 N6/66²) — — — — 5 N66 — — — — — PP — — — — —MAH-g-EEA — — — — — <Rubber> Br-IPMS 60 60 60 35 35 HNBR — — — 10 10 ENR— — — 5 5 <Vulcanization system> Zinc oxide 0.3 0.3 0.3 0.3 0.3 Zincstearate 1.2 1.2 1.2 0.05 0.05 Stearic acid 0.6 0.6 0.6 0.12 0.12 Sulfur— — — 0.05 0.05 TT — — — 0.12 0.12 M — — — 0.05 0.05 Method of chargingWhen When When When When cross-linking mixing mixing mixing mixingmixing agent rubber rubber rubber rubber rubber Gelation rate (%) 83 8585 75 75 Young's modulus 87 70 51 60 67 (MPa) Air permeation 11 14 18 139 coefficient (×10⁻¹² cc · cm/cm² · sec · cmHg) 40% compression 260 400Stopped Stopped Stopped set durability after after after (10,000×) 500500 500 Tire inside Good Good Fair Good Good appearance Air leakage 1.82.2 2.8 2.2 1.7 performance (% drop internal pressure/month) Tiredurability Good Good Good Good Good Mw/Mn after matrix 2.5 2.3 2.2 2.82.8 resin extraction Comp. Comp. Comp. Comp. Comp. Ex. I-6 Ex. I-1 Ex.I-2 Ex. I-3 Ex. I-4 Ex. I-5 <Resin> N11 24 24 24 — — 24 N6/66¹⁾ 11 11 11— — 11 N6/66²⁾ 5 5 5 — — 5 N66 — — — — 40 — PP — — — 40 — — MAH-g-EEA —— — — — — <Rubber> Br-IPMS 35 35 35 60 60 35 HNBR 10 10 10 — — 10 ENR 55 5 — — 5 <Vulcanization system> Zinc oxide 0.3 — — 0.3 0.3 1.5 Zincstearate 0.05 — — 1.2 0.05 0.15 Stearic acid 0.12 — — 0.6 0.12 0.6Sulfur 0.05 0.05 — — 0.05 0.15 TT 0.12 0.12 — — 0.12 0.6 M 0.05 — — —0.05 0.15 Method of At When When When When When charging cross- twin-mixing mixing mixing mixing mixing linking agent screw rubber rubberrubber rubber rubber mixing Gelation rate 73 48 40 78 Rubber 97 (%)scorch- ing when mixing Young's modu- 63 61 58 70 — 92 lus (MPa) Airpermeation 8 8 9 87 — 10 coefficient (×10⁻¹² cc · cm/cm² · sec · cmHg)40% compres- 460 40 10 350 — 40 sion set dura- bility (10,000×) Tireinside Good Good Good Poor — Good appearance Air leakage 1.6 1.6 1.713.5 — 1.8 performance (% drop inter- nal pressure/ month) Tiredurability Good Poor Poor Good — Poor Mw/Mn after 4.9 2.6 2.5 Not — 3.5matrix resin meas- extraction ured

[0147] As seen from the results of Table I-1, it was learned that thetires of Examples I-1 to I-6 using thermoplastic elastomer compositionsaccording to the present invention as the tire air permeation preventivelayer are all superior in flexibility and durability and superior in thetire inside appearance and air permeation preventive property and,further, are superior in terms of the fatigue endurance and maintain agood balance of these properties.

Example II-1 and Comparative Examples II-1 to II-3

[0148] The components and ratios of formulation (parts by weight) of therubber composition (A) and rubber composition (D) used in Example II-1and Comparative Examples II-1 to II-3 and the measurements of their meltviscosities are shown in the following Table II-1. TABLE II-1 RubberRubber composition composition Rubber composition (A) (D) Br-IPMS(Exxpro 89-1) 100 — Br-IPMS (Exxpro 89-4) — 100 Zinc white 0.15 0.15Stearic acid 0.6 0.6 Zinc stearate 0.3 0.3 Viscosity (poise), 1900 2100230° C., 1150/s (no vulcanization system when measuring viscosity)

[0149] (Note)

[0150] *1: The vulcanization system of the rubber composition mixed inadvance by Bambury mixer.

[0151] *2: Br-IPMS: Bromide of isobutylene-p-methylstyrene copolymer(made by Exxon Chemical).

[0152] Further, the components and ratios of formulation (parts byweight) of the resin (B) used in Example II-1 and Comparative ExamplesII-1 to II-3 and the measurements of their melt viscosities are shown inthe following Table II-2. TABLE II-2 Resin Resin Resin Resin (B) (1) (2)(3) Nylon 666 (Amilan  50 — — CM6001/Toray) Nylon 666 (5013B/Ube —  50 50 Industry) Nylon 11 (Rilsan — —  50 BMN 0/Atochem) Nylon 11 (RilsanBESN 0  50  50 — TL/Atochem Viscosity (poise), 230° C., 1900 1050 8001150/s

[0153] The test methods used for evaluation of the Examples andComparative Examples were as follows:

[0154] 1) Melt Viscosity

[0155] Here, the melt viscosity means the melt viscosity of anytemperature and composition at the time of the mixing. The meltviscosity of a polymer material is dependent on the shear rate(sec^(—1)) and shear stress, and therefore, the stress and shear rate ofthe polymer material at any temperature in the molten state flowingthrough a capillary tube, in particular, the temperature region at thetime of mixing, were measured and the melt viscosity measured by thefollowing formula (1):

η=δ/{dot over (γ)}  (1)

[0156] (where, δ: shear force, {dot over (γ)}: shear rate)

[0157] Note that for the measurement of the melt viscosity, a capillaryrheometer Capillograph 1C made by Toyo Seiki was used.

[0158] 2) Test Methods of Tensile Strength and Elongation

[0159] This was based on JIS K6251 “Tensile Test Method of VulcanizedRubber”. The thermoplastic elastomer composition prepared by the mixingwas pelletized, then passed through a T-die by a single-screw extruderto form it into a film of a width of 350 mm and thickness of 100 μm. Theobtained film was punched out into JIS No. 3 dumbbell shapes in parallelto the direction of extrusion at the time of extrusion of the film.

[0160] 3) Method of Measurement of Rubber Particle Size

[0161] The film prepared in the test of the tensile strength andelongation was cut by a microtome etc. to prepare ultrathin slices whichwere then dyed by O_(s)O₄ etc. and directly examined using atransmission electron microscope (Hitachi H-800 Type).

[0162] 4) Constant Strain Test

[0163] Rubber-based cement of the formulation shown in the test methodof Examples I-1 etc., that is, “3) Test Method of 40% Compressive SetDurability”, was brushed on a thermoplastic elastomer composition filmand dried. Tire carcass use rubber (no carcass) of the formulation shownin the test method of Examples I-1 etc., that is, “3) Test Method of 40%Compressive Set Durability”, was superposed on this, then the assemblywas vulcanized at 180° C. for 10 minutes to prepare a 2 mm thickfilm/rubber laminate. This was punched out to a JIS No. 2 dumbbell shapewhich was used for a durability test at a cycle of 5 Hz while applying40% constant strain. (Note: the test was stopped for samples notbreaking after 10,000,000 times.)

[0164] 5) Tire Durability Test

[0165] As explained above.

[0166] The settings of the conditions in the first mixing process andthe second mixing process of Example II-1 and Comparative Examples II-1to II-3 and the test results are shown in the following Table II-3.TABLE II-3 Comp. Comp. Comp. Ex. II-1 Ex. II-1 Ex. II-2 Ex. II-3 Firstmixing Resin (1) 50 35 — — process Resin (2) — — 50 — Resin (3) — — — 35Rubber composition 50 65 50 65 (A) Second mix- First mixing 70 — 70 —ing process composition (C) Rubber composition 30 — 30 — (D) Rubbercomposi- 65/35 65/35 65/35 65/35 tion/resin ratio (wt %) Viscosity Firstmixing process 1 Mixing 1.8 2.4 ratio Second mixing 1.1 impos- 1.5 —(rubber process sible composition/ resin) Tensile strength 31 — 24 21(MPa) Elongation (%) 450 — 350 330 Rubber particle size 0.5 — 3.5 5 (μm)Constant strain set Stopped — 6 4 test after 10 million million milliontimes times times Tire durability test Good — Fair Poor

[0167] Further, the microstructures in the thermoplastic elastomersobtained by Example II-1 and Comparative Example II-2 are shown in FIG.1 and FIG. 2.

[0168] The following is learned from the results of Table II-3 and FIGS.1 and 2.

[0169] From Comparative Examples II-1 and II-3, it is learned that inthe conventional production processes, it is necessary to raise theratio of viscosities for increasing the rubber component (give adifference). However, by raising the ratio of viscosities, the rubberparticle size becomes larger and, as a result, the constant strain testresistance and the tire durability are decreased. Further, from acomparison of Example II-1 and Comparative Example II-2, it is learnedthat by controlling the ratio of viscosities, the rubber particle sizebecomes smaller and the constant strain test resistance and tiredurability become better. Therefore, by using the present invention, itis possible to obtain a thermoplastic elastomer composition which isflexible, high in strength, high in elongation, and superior indurability.

Examples III-1 to III-5 and Comparative Examples III-1 to III-2

[0170] Each of thermoplastic elastomer compositions prepared by mixingaccording to the components and formulation conditions of the Examplesshown in the following Table III-1 was pelletized, then passed through aT-die by a single-screw extruder to form a film of a width of 350 mm andthickness of 100 μm. These were used for test samples of the tests.

Preparation of Test Samples

[0171] First, the rubber component of Table III-1 was mixed using aninternal mixer, then extruded into strands and pelletized. Next, thematrix resin component, dispersed resin component, and rubber componentwere dry blended, then charged from a first charging port of a JSW TEX44twin-screw mixing extruder and melt mixed at 230° C. for about 10minutes. The mixed matter obtained was extruded from the front of thetwin-screw mixing/extruder into strands, water-cooled, and thenpelletized. The pelletized mixed matter was melted by a 40 mm diametersingle-screw extruder for a resin at a speed of 40 rpm at 230° C. toprepare a film having a width of 350 mm and thickness of 100 μm.

[0172] Note that the melt viscosities of the rubber and resin componentsof the thermoplastic elastomer composition used in the preparation ofthe test samples were as shown below. Melt viscosity (poise) at 230° C.,1150/sec Br-IPMS rubber composition (Exxpro 1030 89-4, Exxon Chemical)N11 resin (Rilsan BMN 0, Atochem) 855.7 N12 resin (Rilsan AMN 0,Atochem) 840 N612 resin (D-18, Daicel -Hüls) 1047 N666 resin (1) (5613B,Ube 995.3 Industry) N666 resin (2) (Amilan CM6001, 1800 Toray)

[0173] The test methods used for evaluation in the Examples andComparative Examples were as follows:

[0174] Melt Viscosity

[0175] As explained above.

[0176] Compressive Set Test

[0177] Rubber-based cement of the formulation shown in the test methodsof Examples I-1 etc., that is, “3) Test Method of 40% Constant StrainDurability”, was brushed on a thermoplastic elastomer composition filmand dried. The tire carcass use rubber (no carcass) of the formulationshown in the test methods of Examples I-1 etc., that is, “3) Test Methodof 40% Constant Strain Durability”, was superposed, then the assemblywas vulcanized at 180° C. for 10 minutes to prepare a 2 mm thickfilm/rubber laminate. This was punched out to a JIS No. 2 dumbbell shapewhich was used for a durability test at a cycle of 5 Hz while applying30.6% strain. (The test was stopped for samples not breaking after10,000,000 times.)

[0178] Test Method of Air Permeation Coefficient of Film

[0179] As explained above.

[0180] Measurement Method of Particle Size of Rubber and Dispersed Resin

[0181] The prepared film was cut by a microtome etc. to prepareultrathin slices which were then dyed by RuO₄ etc. and directly examinedusing a transmission electron microscope (Hitachi H-800 Type).

[0182] The test results of Examples III-1 to III-5 and ComparativeExamples III-1 to III-2 are shown in the following Table III-1. TABLEIII-1 Comp. Comp. Ex. III-1 Ex. III-1 Ex. III-2 Ex. III-2 Ex. III-3 Ex.III-4 Ex. III-5 Rubber: IPMS formulation *1 45 45 45 45 45 45 45Thermoplastic resin N11 33 33 44 44 11 — — N12 — — — — — 33 — N612 33N666(1) 22 — 11 — 44 22 22 N666(2) — 22 — 11 — — — Rubber/resin ratio45/55 45/55 45/55 45/55 45/55 45/55 45/55 Rubber/resin viscosity ratio1.13 0.84 1.18 0.99 1.06 1.14 1.02 N666/N11 (or N12, or N612) ratio 4/64/6 2/8 2/8 8/2 4/6 4/6 N666/N11 (or N12, or N612) 1.16 2.14 1.16 2.140.86 1.18 1.05 viscosity ratio Constant Strain Durability test 1000> 6001000> 600 1000> 1000> 1000> 10° C. (10000X) Test −20° C. (10000X) 790 201000> 300 500 810 1000> Air permeation coefficient × 15.8 16.0 28.0 27.510.4 20.3 18.1 10⁻¹² (cc · cm/cm² · sec · cmHg) Average particle size ofresin 0.5 to 9 15 to 49 0.5 to 12 to 35 0.5 to 0.8 to 0.5 to (μm) 8.08.0 10 5.0 Average particle size of rubber 1.5 to 10 to 20 1.0 to 0.5 to1.0 to 1.0 to 0.6 to (μm) 8.0 8.0 6.0 7.0 10 6.0 (Note) *1: Compositionof Br—IPMS Formulation Parts by Weight Br—IPMS (Exxpro 89-4, made byExxon Chemical) 100 ZnO (Zinc White No. 3, made by Seido Chemical) 0.5Stearic acid (Beads Stearic Acid, made by NOF Corporation) 2 Zincstearate 1

[0183] According to the results of Table III-1, it is learned that thecompositions of the Examples of the present invention improve thedurability under low temperature compared with the Comparative Examplesby bringing the viscosity ratio of the blended resin close to 1.

INDUSTRIAL APPLICABILITY

[0184] In the present invention, by controlling the dispersed particlesize of the rubber in the thermoplastic elastomer composition and theblended resin structure of the matrix phase, it was found that thedurability, particularly the durability up to stringent times of 10° C.,0° C., −20° C., or −40° C. was remarkably improved while maintaining thegas permeation preventive property. Therefore, the thermoplasticelastomer composition of the present invention can be effectively usedas a member of a product requiring durability such as elongationflexural fatigue in a wide temperature range from ordinary temperatureto a low temperature region such as the inner liner member of apneumatic tire, a hose member, a belt member, and a fender.

1. A thermoplastic elastomer composition comprising an elastomercomponent containing a nylon resin having a melting point of 170 to 230°C. and a halide of an isobutylene-p-methylstyrene copolymer, which isdynamically vulcanized to a gelation rate of 50 to 95%:
 2. Athermoplastic elastomer composition as claimed in claim 1 , wherein thenylon resin is composed of nylon 11 or nylon 12 and nylon 6/66 copolymerat a composition of 10/90 to 90/10.
 3. A thermoplastic elastomercomposition as claimed in claim 2 , wherein a molecular weightdistribution (Mw/Mn) of a blend of the nylon 11 or nylon 12 and thenylon 6/66 copolymer in the thermoplastic elastomer composition isMw/Mn<10.0.
 4. A process for producing a thermoplastic elastomercomposition comprising the step of previously mixing a cross-linkingagent for cross-linking the elastomer component into the elastomercomponent.
 5. A pneumatic tire having a thermoplastic elastomercomposition according to any one of claims 1 to 4 as an air permeationpreventive layer.
 6. A process for producing a thermoplastic elastomercomposition comprising the steps of: mixing a rubber composition (A) anda thermoplastic resin (B) under conditions of the following equations(I) and (II): (φ_(A)/φ_(B))×(η_(B)/η_(A))<1.0   (I)0.8<(η_(A)/η_(B))<1.2   (II) wherein φ_(A): volume fraction of rubbercomposition (A), φ_(B): volume fraction of resin (B), η_(A): meltviscosity of rubber composition (A), η_(B): melt viscosity of resin (B)to form a composition (C); and mixing the resultant composition (C) anda rubber composition (D) under conditions of the following equations(III) and (IV): (φ_(D)/φ_(C))×(η_(C)/η_(D))<1.0   (III)0.8<(η_(C)/η_(D))<1.2   (IV) wherein φ_(D): volume fraction of rubbercomposition (D), φ_(C): volume fraction of composition (C), η_(D): meltviscosity of rubber composition (D), η_(C): melt viscosity ofcomposition (C)).
 7. A pneumatic tire comprising a thermoplasticelastomer composition prepared by the process according to claim 6 , asan air permeation preventive layer of the tire.
 8. A thermoplasticelastomer composition comprising an elastomer composition (A′) as adispersion phase and a thermoplastic resin composition (B′) as a matrix,said and having composition (B′) composed of a blend of at least twothermoplastic resins, wherein the dispersed particle size of theelastomer composition (A′) is not more than 10 μm and the particle sizeof a resin composition (D′) dispersed in a matrix resin composition (C′)in the thermoplastic resin composition (B′) is smaller than the particlesize of the dispersed rubber.
 9. A thermoplastic elastomer compositionas claimed in claim 8 , wherein the elastomer composition (A′) and thethermoplastic resin composition (B′) satisfy the following equations (V)and (VI): (φ_(d)/φ_(m))×(η_(m)/η_(d))<1.0   (V) 0.8<(η_(m)/η_(d))<1.2  (VI) wherein φ_(d): volume fraction of elastomer composition (A′),φ_(m): volume fraction of thermoplastic resin composition (B′), η_(d):melt viscosity of elastomer composition (A′), η_(m): melt viscosity ofthermoplastic resin composition (B′) and the matrix resin composition(C′) and dispersed resin composition (D′) in the thermoplastic resincomposition (B′) satisfy the following equations (VII) and (VIII):(φ_(D′)/φ_(C′))×(η_(C′)/η_(D′))<1.0   (VII) 0.8<(η_(C′)/η_(D′))<1.2  (VIII) wherein φ_(D′): volume fraction of dispersed resin composition(D′), φ_(C′): volume fraction of matrix resin composition (C′), η_(D′):melt viscosity of dispersed resin composition (D′), η_(C′): meltviscosity of matrix resin composition (C′).
 10. A thermoplasticelastomer composition as claimed in claim 8 or 9 , wherein the elastomercomponent contained in the elastomer composition (A′) is at least oneelastomer selected from the group consisting of diene rubbers and thehydrates thereof, olefin rubbers, halogen-containing rubbers, siliconerubbers, a sulfur-containing rubbers, a fluoro rubbers, andthermoplastic elastomers.
 11. A thermoplastic elastomer composition asclaimed in any one of claims 8 to 10 , wherein the thermoplastic resincomponent contained in the thermoplastic resin composition (B′) is atleast one thermoplastic resin selected from the group consisting ofpolyamide resins, polyester resins, polynitrile resins, polymethacrylateresins, polyvinyl resins, cellulose resins, fluoro resins, and imideresins.
 12. A thermoplastic elastomer composition as claimed in any oneof claims 8 to 11 , wherein a blend of at least two polyamide resins isselected as the thermoplastic resin composition (B′).
 13. Athermoplastic elastomer composition as claimed in any one of claims 8 to12 , wherein a polyamide resin having at least seven methylene groupswith respect to one amide group is contained as the matrix resincomposition (C′) in the thermoplastic resin composition (B′) and apolyamide resin having less than seven methylene groups with respect toone amide group is contained as the dispersed resin composition (D′).14. A pneumatic tire comprising a thermoplastic elastomer composition asclaimed in any one of claims 8 to 13 as an air permeation preventivelayer.
 15. A hose comprising a thermoplastic elastomer compositionaccording to any one of claims 8 to 13 as at least one of a hose outertube material adjacent to a reinforcing layer, an inner layer materialof an inner tube, an outer layer material of an inner tube, and a spacebetween reinforcing layers.